Collagen-containing sheet materials are known. For example, published patent application EP 2 098 255 A2 (AAP Biomaterials GmbH) discloses a method for producing collagen material. As a starting material, porcine skin is used, which is purified by an alkaline, oxidative, and acidic treatment to remove grease and other foreign matter.
The porcine skin is comminuted mechanically, and subsequently an aqueous suspension is produced from the porcine skin, which is adjusted to a neutral to slightly alkaline pH by addition of a phosphate buffer.
Thereby, a three-dimensional network of collagen fibrils is formed. The suspension containing this network is lyophilized. The resulting sponge-like or non-woven sheet material is highly porous, very flexible, and does not adhere to surgical instruments, in both its dry and wet states.
For some applications, a drawback of the material is that it can be badly cut in the rehydrated state, due to its very high flexibility. Further, the material swells in the wet state.
In some applications it is particularly disadvantageous that the sheet material is opaque. So the surgeon cannot look through the sheet material, which would strongly facilitate accurate placement of the sheet material in many cases.